Threading via Machinist Handbook (measuring)

[devils4ever]

I started with the thread wires and decided to switch to a Shars thread mic. Great decision! Those wires are tricky to handle. I can get a reading much quicker than with the wires.

I use the MH for reference, but most of the time I use an online thread calculator. This gives all the parameters you need for the thread you are cutting. MH is great but it's easy to misread the table with all those entries. Plus, I print out the page and keep my MH pages clean.

For cutting an external thread, I turn down the diameter to within the range listed. Then, I cut the thread until the pitch diameter is within the range listed.

 

[ThinWoodsman]

Depending on how old the plane is it might be an old style "V" thread.

Plane is somewhere between 1930s and 1950s. I'm guessing Whitworth, which Stanley was rather fond of back then.

Looks like there is a gage for whitworth; the problem with the gage is false positives. The 27-TPI American/Unified gage seemed almost right, the 28 TPI seemed spot on.

The only way I know of to determine the thread form is to magnify it with a stark background, snap a photo, and then measure the angles and examine the crest manually.

 

[mickri]

I have both imperial and whitworth thread gauges. Put a piece of white paper behind the threaded rod with good lighting. If the threads are whitworth you should be able to see the white paper between the 60 degree imperial thread gauge and the side of the 55 degree whitworth thread.